1. Field of the Invention
Implementations of various technologies described herein generally relate to seismic data processing.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Seismic exploration is widely used to locate and/or survey subterranean geological formations for hydrocarbon deposits. Since many commercially valuable hydrocarbon deposits are located beneath areas of land and bodies of water, various types of land and marine seismic surveys have been developed.
In a typical land or marine seismic survey, seismic sensors are installed in specific locations around an area of the earth in which hydrocarbon deposits may exist. Seismic sources, such as vibrators or air guns, may move across the area and produce acoustic signals, commonly referred to as “shots,” directed down to the earth, where they are reflected from the various subterranean geological formations. Reflected signals are received by the sensors, digitized, and then transmitted to a survey database. The digitized signals are referred to as seismic data. The ultimate aim of this process is to build a representation of the subterranean geological formations beneath the surface of the earth. Analysis of the representation may indicate probable locations of hydrocarbon deposits in the subterranean geological formations.
Prior to installing seismic sensors and receivers in specific locations around an area of the earth, computers may be used to model how seismic sensors and receivers may react in certain areas of the earth. The models created by the computers may create an illumination map which may be used to determine where the seismic sensors and receivers should be installed. The illumination map may quantify how effective the earth is in propagating energy to and from a target area of the earth. The target area of the earth may represent an area of the earth where the subterranean geological formations beneath the surface of the earth are located. In order to create an illumination map, the computers may be used to perform numerical simulations of wavefield propagations on an earth model. In these simulations, source and receiver configurations are placed on the earth model in locations that represent the surface of the earth, the surface of a body of water on the earth, the seabed on the earth or a borehole in the earth. One method of numerical wave propagation that is commonly used is ray-tracing.
Ray-tracing is implemented by propagating rays from potential source locations in the earth model to the target areas in the earth model. The target areas may link the potential source locations with the subterranean geological formations inside the earth. For example, the target area may include a reflector near a potential hydrocarbon reservoir. The target area may also include receiver locations where reflections may be recorded. The ray-tracing method is typically computationally efficient, but it may fail in areas where complex variations exist near the target area. Complex variation may include the presence of salt bodies, carbonates, basalts, shale diapirs or other geologic situations that create complexity.